Latch mechanism for fire and smoke dampers and the like

ABSTRACT

A resettable latch mechanism for holding an operating member, the release of which causes the closing of a fire damper, smoke hatch, fire door or the like, when an electrical circuit connected thereto is energized. The latch mechanism has a latch plate and a latch element cooperating with the latch plate, either the latch plate or the latch element being a movable member, and an actuator adapted to move the movable member responsive to energization of the electrical circuit.

llited States Patent 1 Scharres [451 Apr. 30, 1974 LATCH MECHANISM FORFIRE AND SMOKE DAMPERS AND THE LIKE [76] Inventor: Harry J. Scharres, 10Gilbert Ave,

Clarendon Hills, 111. 60514 [22] Filed: Jan. 29, 1973 [21] Appl. No.:327,455

52 us. Cl. 74/2 [51] Int. Cl G05g 17/00 [58] Field of Search 74/2 [56]References Cited UNITED STATES PATENTS 978,857 12/1910 Day 74/23,195,433 7/1965 Fernald 74/2 X Primary Examiner-Allan D. HerrmannAttorney, Agent, or FirmW01fe, Hubbard, Leydig, Voit & Osann, Ltd.

[57] ABSTRACT A resettable latch mechanism for holding an operatingmember, the release of which causes the closing of a fire damper, smokehatch, fire door or the like, when an electrical circuit connectedthereto is energized. The latch mechanism has a latch plate and a latchelement cooperating with the latch plate, either the latch plate or thelatch element being a movable member, and an actuator adapted to movethe movable member responsive to energization of the electrical circuit.

7 Claims, 4 Drawing Figures LATCH MECHANISM FOR FIRE AND SMOKE DAMPERSAND THE LIKE The present invention generally relates to fire, smoke andblast dampers or'hatches and, more particularly, to latch mechanisms forautomatically closing such devices responsive to detection of conditionswhich indicate the existence of a fire, excessive smoke or an impendingblast condition.

Since heating and ventilation ducts as well as other air corridors inbuildings may be required to have dampers, hatches or doors which willbe automatically closed when excessive smoke is present or when a firebreaks out, it is desirable to have a latch mechanism for operating suchdampers or hatches if either condition is present. Latching mechanismsthat are electrically actuated by either smoke or fire detectors areconveniently used, since either of these conditions will result in thedampers and hatches being closed which may not be done from onlymechanical temperature responsive devices.

Release mechanisms typically include fusible links which can be actuatedby a small electrical charge to release a smoke-damper or the like forclosing when a system detects excessive smoke or a fire or an impendingblast condition. One disadvantage of such fusible links is that they areessentially one-use devices and must be replaced after they areactuated. It should be apparent that a large building may include aconsiderable number of dampers, firedoors and hatches and would therebyutilize a significant number of such fusible links. In the event thereis a malfunction within the system which triggers .their actuation,considerable expense may be experienced in replacing all of the links.Additionally, while their reliability is often stated to be quite high,it is unknown whether a particular fusible link will operate until it isin fact actuated and, once this is confirmed, it is necessary'to replacethe very fusible link that was actuated.

Accordingly, it is an important object of the presentinvention toprovide a latch mechanism that may be which may be placed in a cocked orready condition and which will thereafter release and close a firedamper, smoke hatch or the like responsive to energization of anelectrical circuit and which may be thereafter returned to its readycondition by a relatively simple manipulation of the mechanism.

Still another object of the present invention lies in the provision forproducing a latch mechanism having the above advantages from arelatively small number of components and thereby insure lowmanufacturing costs.

Yet another object of the present invention is to provide a releasemechanism having the above advantages which, because of its design andconstruction, may be tested in the actual environment in which it is towork, and thereby provide definite assurance that the system willachieve its intended purpose. A closely related ob-' ject lies in theprovision for enabling such testing without incurring any expense interms of replacing any components within the mechanism to return it to aready condition.

Other objects and advantages will become apparent from the followingdetailed description, while referring to the attached drawings, inwhich:

FIG. 1 is a side elevation of an actuator and latch mechanism embodyingthe present invention, shown in ready condition together with anoperating member the release of which will cause the closing of a firedamper, smoke hatch or the like; I

FIG. 2 is a section taken generally along the line 22 of FIG. 1;

FIG. 3 is a side elevation of the mechanism shown in FIG. I,particularly illustrating the latching mechanism in its releasedcondition; and

FIG. 4 is a side elevation of an alternative constructionalso embodyingthe present invention and is illustrated in a ready condition.

While the present invention willbe described in connection with certainpreferred embodiments, it should be understood that it is not intendedto limit the invention to these particular embodiments. On the contrary,it is intended to cover all alternatives, modifications and equivalentsas may be included within the spirit and' scope of the invention asexpressed in the appended claims.

Turning now to the drawings and particularly FIGS.

1-3, a latch mechanism, indicated generally at 10, is shown togetherwith a flexible link, which in the illustrated drawings is shown to bechain 12 adapted to operate a fire damper, fire door, smoke hatch or thelike (not shown). The chain 12 is held by the latch mechanism 10 so thatwhen themechanism releases the chain, it will cause the damper or hatchto close and confine smoke or fire to a local area and thereby preventrapid spreading through a heating and ventilating duct, for example, aswell as other corridors in which such dampers and hatches arepositioned. The latch mechanism 10 embodying the present invention isadapted to release the chain 12 responsive to the energization of anelectrical circuit which is 'not shown except for electrical lines 14that terminate in the illustrated latch mechanism. It is intendedhowever, that the latch mechanism 10 be a part of an overall systernthatincorporates smoke detectors, fire detectors as well as devices whichwould detect an impending blast condition and in the event any one ofthese detectors would be actuated, would energize an electrical circuitthat would resultin current flowing through lines 14 to actuate thelatch mechanism embodying the present invention.

The embodiment shown in FIGS. 1-3 includes a generally horizontal frame16 having an upturned end portion 18 and an electrically activatedactuator 20 having a movable piston 22 for contacting a side portion 24of a generally U-shaped member, indicated generally at 26, which alsohas a middle portion 28 and a second side portion 30. The U-shapedmember 26 includes generally horizontal elongated slots 32 in each sideportion thereof through which the frame 16 may pass, so that theU-shaped member 26 is movable relative to the frame and is therebyresponsive to the action of the piston 22 of the actuator 20. A spring34is interposed between the upturned end portion 18 of the frame and theside portion 30 of the U-shaped member to normally bias the U-shapedmember toward the position shown in FIG. 1 wherein the latch mechanismis in a cocked or ready condition. A stop '36 may be provided to limitthe leftward movement of the U-shaped member 26. In operation,energization of the electrical circuit through lines 14 will cause thepiston 22 of the actuator to move toward the right and will move thelatch plate 26 to the right and compress the spring 34 all as shown inFIG. 3. 1

The actuator 20 may be of many different constructions. For example, theelectrical line 14 may be continuous through a heating coil containedwithin the actuator for heating a heat expandable material or fluidwhich, when it is expanded, will force the piston 22 to the right aspreviously described. This type of actuator has an inherent advantage inthat a time delay is experienced before the chain is released due to thefact that it requires some period of time before the heating coil willcause sufficient expansion of the material to move the piston 22 througha distance that will cause the release of the chain. However, it shouldbe understood that other devices such as solenoids or the like may beconveniently used, and if such devices act instantaneously, conventionalelectrical or electromechanical delay devices may be incorporated withinthe system if some delay period is desired. In this connection, it ispreferred that the operation of the mechanism be dey layed for a shortperiod so that any transient electrical signals or inadvertentenergization of the system by persons within a building incorporatingsuch a system will not actuate all of the release mechanisms therein.

To release the chain 12, the mechanism embodying the present inventionincludes a latch element, indicated generally at 40, which cooperateswith a latch plate 42 carried by the U-shaped member 26 so as to bemovable therewithflh'e latch element 40 includes an elongated member 44shown to be one end of a wire spring that is wrapped around a screw 46mounted to a bracket 48 which is secured to the frame 16, the other freeend 50 of the wire spring contacting the underside of the frame 16.Thus, the free end 44 of the wire spring is biased in a downwarddirection as shown. It should be understood that the elongated memberneed not, in and of itself, bea part of a wire spring, but may have aseparate spring or the like acting upon a nonresilient member.

The latch member 40 is held' in position by the latch plate 42 which issuitably secured to the middle portion 28 of the U-shaped member and hasa suitable slot 52 adapted to receive the elongated member 44 as isshown in FIG. 2.,Thus, the chain is held by the elongated member whenthe latch plate 42 is in the position shown in FIG. '1 and is adapted torelease the chain as the piston '22 moves the U-shaped member 26 to theright so that the latch plate 42 moves away from the elongated member asufficient distance to release the chain as is shown in FIG. 3.

To return the latch mechanism to its ready or cocked the elongatedmember being attached to the frame 16 and the latch plate 42 beingmovable relative thereto, it should also be realized that the latchplate could be fixed to the frame 16 and-that the latch member bemounted upon the U-shaped member 26 for movement. Moreover, while theactuator 20 is specifically described as having its piston 22 extendableresponsive to energization of the electrical circuit, an actuator couldbe utilized wherein the piston is normally extended with theenergization of the electrical circuit, and responsive to deenergizationthereof cause retraction of the piston 22. With such an arrangement, theactuator 20 may be positioned where'the spring 34 is shown so that thepiston would be attached to and be adapted to pull the side 30 of theU-shaped member 26 to the right. The spring 34 may then be adjacent theactuator 20 or may be placed where the actuator is positioned in FIG. 1but placed in a tensioned condition rather than a compressed conditionas specifically shown in FIG. 3 so that it would bias the U-shapedmember to the left in either case.

Turning now to the alternative construction also embodying the presentinvention and shown in FIG. 4, a frame 60 having a downwardly turned endportion 62 is provided, with the end portion 62 providing a mountingsurface for an actuator which is shown to be an electromagnet 64connected to the electrical circuit through lines 66. The mechanismincludes a latch element, indicated generally at 68, and similar to thepreviously described latch element 40 shown in FIG. 1, and accordinglyhas an elongated member also comprising one free end of a wire springwhich is wrapped around a screw 72 or the like, the other end 74 ofwhich bears against the underside of the frame 60. The screw is attachedto a support bracket 76 that is attached to the frame 60. v f

To hold the latch element 68, a pivotable, ferromagnetic latch plate 80is provided'and has a slot substantially similar to the slot 52 shown inFIG. 2. The upper end of the latch plate 80 has a perpendicularly bentportion 82 which bears against the underside of the frame 60 to limitthe leftward movement of the lower portion of the latch plate 80 to theposition shown. This prevents the latch plate from moving out of theimmediate proximity and working range of the electromagnet 64. Thepivotable latch plate is mounted to the frame60 by means of a pin 84 orthe like journaled by a pair of downwardly extending ears 86 (only oneof which is shown) that are. attached to or integrally formed with theframe 60. Thus, the lower portion of the latch plate 80 is free to moveto the right shown in phantom.

In operation, energization of the electromagnet 64 will pull the latchplate to the right and release the latch member 68 enabling the chain 12to drop and cause a fire damper, smoke batch or the like to be closed.It should also be understood that the actuator may also be a solenoiddevice which is positively mechanically connected to the latch member sothat when it is energized, it will positively pull the latch plate tothe position shown in phantom and release the latch element. In theevent such an actuator is used with a mechanical connection, the latchplate need not be produced from a ferromagnetic material. It is alsocontemplated that a solenoid device having a mechanical connection maybe used wherein it is adapted to retract and pivot the latch plate tothe position shown in phantom responsive to the deenergization of theelectrical circuit if desired.

To return the mechanism to its cocked or ready condition, the chain ismerely replaced on the elongated member 70 and the elongated member isinserted into the slot in the manner as previously described withrespect to the embodiment shown in FIGS. 1-3.

The elongated member 70 is preferably in a downwardly inclined positionas shown so that a component of force is exerted to the left by virtueof the downward bias of the elongated member 70. This has the effect ofholding the latch 80 in the position shown so that its portion 82 bearsagainst the frame 60. By virtue of this leftward component of force, noother spring or biasing means is required to hold the latch plate in itslatched or ready position.

Thus, the invention described herein represents a marked improvementover existing devices for causing fire dampers and hatches to close andhas many desirable attributes in terms of the ability to actually testthe system. The cost of maintenance of a system incorporating the latchmechanisms embodying the present invention is reduced since they arecapable of being reused by merely returning them to their readycondition without additional expense. The invention described herein isbelieved to satisfy all of the objects that have been previously setforth.

I claim as my invention:

1. A latch mechanism for a fire damper, smoke hatch, fire door or thelike actuable responsive to the energization of an electrical circuit,the combination comprising:

a frame,

a latch plate, support member slidable on frame and carrying said latchplate;

a latch element mounted on the frame and cooperating with said latchplate, said latch element being held by said latch plate in latchedposition;

said latch plate and latch element being movable members;

spring means for resiliently holding one movable member in latchedposition;

an actuator fixed to the frame and having an extendable'piston forcontacting said support member so that extension of said piston movessaid support member and latch plate away from said latch element torelease said latch element responsive to the energization of theelectrical circuit.

2. A latch mechanism as defined in claim 1 wherein said spring means isinterposed between a portion of said frame and said support member, thespring having sufficient force to return said piston to its unextendedposition when said circuit is deenergized.

3. A latch mechanism for a fire damper, smoke hatch, fire door or thelike actuable responsive to the energization of an electrical circuit,the combination comprising:

a frame,

a latch plate mounted on the frame;

a latch element mounted on the frame and cooperating with said latchplate, said latch element including an elongated member operablyconnected to said frame and extending to and being retained by saidlatch plate when in latched condition;

said latch plate and latch element being movable members;

spring means normally biasing said elongated member in a downwarddirection, said elongated member being inclined at an acute anglerelative to said latch plate such that said elongated member exerts aforce upon said latch plate in a direction toward said latch element tohold said latch plate in latched condition;

an actuator fixed to the frame for moving said latch plate away fromsaid elongated member to release the same responsive to energization ofthe electrical circuit.

4. A latch mechanism as defined in claim 3 wherein said latch plateincludes a slot having a retention surface to permit the insertion andretention of said elongated member therein.

5. A latch mechanism as defined in claim 3 wherein said elongated membercomprises one free end of a wire spring wrapped around a pin, the otherfree end of which contacts the underside of said frame-so as to normallybias said elongated member in a downward direction so that upon releasethereof by said latch plate, said elongated member will move downwardlyaway from said latch plate.

6. A latch mechanism as defined in claim 3 wherein said latch plate ispivotally mounted upon said frame, the lower end portion of the latchplate including a slot having a retention surface for holding saidelongated member, said actuator being located adjacent said latch plateand adapted to pivot said latch plate when said electrical circuit isenergized, said pivoting movement of the latch plate releasing theelongated member.

7. A latch mechanism for a fire damper, smoke hatch, fire door or thelike actuable responsive to the energization of an electrical circuit,the combination comprising:

a frame,

a latch plate movably mounted on the frame;

a latch element comprising a wire spring wrapped around a pin, one freeend of said spring cooperating with said latch plate and being held bysaid latch plate in latched position, the other free end of said springcontacting the underside of said frame so as to normally bias said freeend of said spring in a downward direction so that upon release thereofby said latch plate, said free end of said wire spring will movedownwardly away from said latch plate; and

an actuator fixed to the frame and adapted to move said latch plate torelease said free end of said wire spring responsive to the energizationof the electrical circuit.

1. A latch mechanism for a fire damper, smoke hatch, fire door or thelike actuable responsive to the energization of an electrical circuit,the combination comprising: a frame, a latch plate, support memberslidable on frame and carrying said latch plate; a latch element mountedon the frame and cooperating with said latch plate, said latch elementbeing held by said latch plate in latched position; said latch plate andlatch element being movable members; spring means for resilientlyholding one movable member in latched position; an actuator fixed to theframe and having an extendable piston for contacting said support memberso that extension of said piston moves said support member and latchplate away from said latch element to release said latch elementresponsive to the energization of the electrical circuit.
 2. A latchmechanism as defined in claim 1 wherein said spring means is interposedbetween a portion of said frame and said support member, the springhaving sufficient force to return said piston to its unextended positionwhen said circuit is deenergized.
 3. A latch mechanism for a firedamper, smoke hatch, fire door or the like actuable responsive to theenergization of an electrical circuit, the combination comprising: aframe, a latch plate mounted on the frame; a latch element mounted onthe frame and cooperating with said latch plate, said latch elementincluding an elongated member operably connected to said frame andextending to and being retained by said latch plate when in latchedcondition; said latch plate and latch element being movable members;spring means normally biasing said elongated member in a downwarddirection, said elongated member being inclined at an acute anglerelative to said latch plate such that said elongated member exerts aforce upon said latch plate in a direction toward said latch element tohold said latch plate in latched condition; an actuator fixed to theframe for moving said latch plate away from said elongated member torelease the same responsive to energization of the electrical circuit.4. A latch mechanism as defined in claim 3 wherein said latch plateincludes a slot having a retention surface to permit the insertion andretention of said elongated member therein.
 5. A latch mechanism asdefined in claim 3 wherein said elongated member comprises one free endof a wire spring wrapped around a pin, the other free end of whichcontacts the underside of said frame so as to normally bias saidelongated member in a downward direction so that upon release thereof bysaid latch plate, said elongated member will move downwardly away fromsaid latch plate.
 6. A latch mechanism as defined in claim 3 whereinsaid latch plate is pivotally mounted upon said frame, the lower endportion of the latch plate including a slot having a retention surfacefor holding said elongated member, said actuator being located adjacentsaid latch plate and adapted to pivot said latch plate when saidelectrical circuit is energized, said pivoting movement of the latchplate releasing the elongated member.
 7. A latch mechanism for a firedamper, smoke hatch, fire door or the like actuable responsive to theenergization of an electrical circuit, the combination comprising: aframe, a latch plate movably mounted on the frame; a latch elementcomprising a wire spring wrapped around a pin, one free end of saidspring cooperating with said latch plate and being held by said latchplate in latched position, the other free end of said spring contactingthe underside of said frame so as to normally bias said free end of saidspring in a downward direction so that upon release thereof by saidlatch plate, said free end of said wire spring will move downwardly awayfrom said latch plate; and an actuator fixed to the frame and adapted tomove said latch plate to release said free end of said wire springresponsive to the energization of the electrical circuit.